So simple fix and make sure you are using the valid updated mysql client. Of course other options existed like changing the authentication plugin back to mysql_native_password but why bother, use the secure method. This is a very good enhancement for security so do not be shocked if you have some connection issues while you get your connections using this more secure method.

This is likely to trip up a few transactions if you do not review your queries before setting up replication to a new MySQL 8.0 instance. I say that because of how the handling of table maintenance could be impacted. If you write clean queries with "If Exists" it won't be a big problem. Overall it is a more transaction based feature that protects your data and rollback options.

Resource management looks very interesting and I will have to take more time to focus on this as it is a new feature with MySQL 8.0. Overall you can assign groups and no longer have to set priority of query but let your grouping define how a query should behave and resources allotted to it.

My test instance already had binary logs enabled, but they are on by default now along with TABLE based versus file based master & slave info, ( big fan of having that transaction based by default )

Overall keep in mind this is just a first glance at this release and very high level thoughts on it, many other changes exist. Looking over other blog posts about this release as well as the manual and release notes will also help. Certainly download and review as it looks to be very promising for administration, security and replication points of view.